I don't know why this happened for Xavi and Barcelona. He was popular when he was working in Barcelona and he had a good performance in the last season but unfortunately during this season he couldn't have the same good performance anymore and they lost the La Liga title to Real Madrid.
However, Xavi thinks it was because of the bad financial situation in Barcelona and he said they can't buy players like the other team while I think he is right but Laporta doesn't have a good relationship with Xavi after he said that, and that's why it seems we can finally see Hansi Flick working in Barcelona since he is also interested for it.